Sometimes I think layer is the wrong word, because I don't envision each technique on top of another. Instead it's much more three dimensional, holding all this in my head at the same time in balance, and trying to keep it all there without one popping out. It occupies more space than just a stack. Think of a solid sphere (of chocolate, if you like) cut into puzzle piece chunks. They can all fit together, or some can be sticking out or can get squeezed out. And these chunks, you can't just shove one in after another to make the sphere. They have to be held at certain angles at the same time to all fit together or it just won't work. I actually hadn't thought of them as a puzzle sphere before this... I was thinking of a three dimensional space where each element was in its own place, and I had to remember and keep them there. But maybe the sphere puzzle is what I should be thinking of - to fit it all together without pushing any out, because otherwise the pieces won't fit.
Ok so to any readers out there who are singers - does any of this make sense?